Bill and Melinda Gates will make an unusual personal appeal to Washington officials Tuesday night, asking them to continue funding global health initiatives despite the recession and to commit to nearly halve the number of child deaths worldwide by 2025.

"Government funding that's coming from the United States is making a huge difference on the ground in the developing world," Melinda Gates said in an interview last week. Particularly over the past four to five years, she said, "it's really palpable -- it's making a huge difference saving lives."

The Bill & Melinda Gates Foundation is the largest private foundation in the world. But Gates said that even with its great wealth, the fund is focused on being a catalyst for much larger government-funded projects in health and education. "We have put about $11.9 billion in global health since the inception of this," she said, most of it within the past decade. "Our money is tiny."

The U.S. government's annual contribution to global health initiatives has increased dramatically in recent years, from $1.5 billion in 2001 to $7.7 billion in 2009.

Last month, the Gates foundation launched an advertising campaign in Washington highlighting the successes it has experienced worldwide.

Bill Gates, who made his fortune as a founder of Microsoft, will appear with his wife Tuesday evening at the Shakespeare Theatre Company's Sidney Harman Hall in downtown Washington. They will address members of Congress, the U.S. global AIDS and malaria coordinators, the health policy counselor for the White House Office of Management and Budget and others.

The presentation, separate meetings with lawmakers and the media campaign are meant to show that U.S. funding is saving lives and that the Gateses think child deaths worldwide can be cut from more than 9 million to 5 million a year in the next 15 years. They point to an AIDS program launched in 2003 by President George W. Bush that is estimated to have saved more than 1 million lives. A Bush initiative on malaria reached an estimated 32 million people last year. And the Global Fund to Fight AIDS, Tuberculosis and Malaria, which gets a third of its budget from the United States, helped bring 88 million bed nets treated with insecticide to children at risk of getting malaria from mosquitoes.

"We are concerned because of the economic challenges that a lot of industrial nations are facing," said Jon Liden, spokesman for the Global Fund.

U.S. lawmakers will be debating massive spending programs even as they face an enormous deficit.

Liden said that malaria could be virtually eliminated as a global health problem within a decade and that the transmission of HIV from mothers to children could be by 2015 -- if the funding continues.

The U.S. budget for fiscal 2010 is not yet finalized.

The U.S. spending -- and that of the Gates foundation -- has at times been controversial, said Dean Jamison, professor of global health at the University of Washington.

"We don't have an AIDS vaccine, don't have a malaria vaccine," he said. But the foundation has spurred research, and the money has undoubtedly had an enormous impact, Jamison said.